On the Measurement of the Hubble Constant in a Local Low-density Universe

Astrophysical observations indicate that the \Local Universe" has a relatively lower matter density ( 0) than the predictions of the standard in ation cosmology and the large-scale motions of galaxies which provide a mean mass density to be very close to unity. In such a local underdense region the Hubble expansion may not be representative of the global behaviour. Utilizing an underdense sphere embedded in a at universe as the model of our \Local Universe", we show that the local Hubble constant would be 1.2 { 1.4 times larger than the global value on scale of 80 Mpc, depending on the variation of 0. This may account for the recent measurements of the unpleasantly large Hubble constant of 80 km/s/Mpc using the Cepheid variables in the Virgo cluster and the relative distance between Virgo and Coma cluster and removes the resulted apparent paradox of the age of our universe. Subject headings: cosmology: distance scale { large-scale structure of universe